Brazing is a process in which a brazing alloy is inserted between the surfaces of components, such as metals, to join the components. Typically, a brazing alloy having a liquidus point below the melting point of the components to be joined is disposed between the surfaces of the components. The assembly formed from these components is then heated to a temperature sufficient to melt the brazing alloy so that upon cooling, a strong, ductility and corrosion/oxidation resistance assembly can be formed.
There are many gold-based brazing alloys which contain specific metal additives for desired specific properties. For example, gold-nickel alloys have good resistance to oxidation and high strength. These brazing alloys are particularly useful for joining metal components such as components of turbine and jet engines, Electronics, Automotive, and Marine equipment.
U.S. Pat. No. 3,658,997 discloses a gold-base brazing alloy for use in the fabrication of jewelry articles, jet engines and high quality engineering components comprising 30 to 80 wt. percent gold, 0.5 to 67.5 wt. percent copper and 2.0 to 12.0 wt. percent nickel. Additionally, the brazing alloy may include 0.5 to 7.0 wt. percent chromium and from a trace up to 0.5 wt. percent boron.
U.S. Pat. No. 3,658,997 discloses a Ni—Au base brazing alloy provided with a narrower temperature range between liquidus and solidus temperatures as a result of the combination of Cr and Fe along with Si and B to adjust the position of such range.
U.S. Pat. No. 3,764,307 discloses a nickel-gold base brazing alloy with relatively low gold content that derives its properties from a balance of Au, Si and B in a Ni base. This alloy has a liquidus of less than about 1900° F. for use in joining members intended to operate in the range of up to about 1400° F.
U.S. Pat. No. 4,726,508 discloses a method of brazing corrosion resistant, nickel-based, thin-walled tubing which includes substantial proportions of nickel, chromium and molybdenum to a stainless steel base member using a filler metal, principally comprising gold as a major constituent and nickel as a minor constituent, in a vacuum furnace without introducing stress corrosion cracks in the brazed tubing and also avoiding carbon precipitation.
U.S. Pat. No. 4,302,515 discloses a brazing foil, useful for brazing stainless steels, which has a composition consisting essentially of 0 to about 4 atom percent iron, 0 to about 21 atom percent chromium, 0 to about 19 atom percent boron, 0 to about 12 atom percent silicon, 0 to about 22 atom percent phosphorus and the balance nickel and incidental impurities. In addition to containing the foregoing elements within the above-noted composition ranges, the composition must be such that the total of iron, chromium and nickel ranges from about 76 to 84 atom percent and the total of boron, silicon and phosphorus ranges from about 16 to 24 atom percent.
U.S. Pat. No, 4,764,435 discloses a metal composition usable as a brazing material for bonding a metal to a non-oxide ceramic. The brazing material contains, at least, one or more metals selected from a first group of transition metals consisting of Pt, Pd, Rh, Ir, Ru and Os, and one or more metals selected from a second group of transition metals consisting of Cr, Mn, Fe, Co, Ni and Cu. The material may further contain one or more elements selected from a third group of elements consisting of B, C, Si and P.
Conventional gold-nickel braze alloys have been used for bonding nickel-chromium based components together, such as Inconel components (Inconel is a trademark for a group of corrosion-resistant alloys). Generally these nickel-chromium-based components (superalloy sheet metal components) would be bonded together using the gold-nickel basis alloys at temperatures above 1800° F. This high brazing temperature is generally high enough to coarsen the grain size of the components and thereby reducing their fatigue resistance. To lower the brazing temperature of the braze alloy, a temperature depressant, such as silicon and/or boron, have been used. These temperature depressants have not necessarily provided the positive control of the range between liquidus and solidus temperatures to improve the brazing of the components to be joined. Additionally, boron generally permeates the nickel-chromium-based components (such as stator vanes of jet engines) and if the temperature is too high (approximately 1900° F.), it could coarsen the grain size of the components and thereby permit the boron to diffuse into the components to further degrade the components properties.
It is an object of the present invention to provide a ternary nickel-gold-phosphorus brazing alloy that has the same or better characteristics of conventional gold-metal alloys,
It is another object of the present invention to provide a ternary nickel-gold-phosphorus brazing alloy that has a brazing temperature less than 1830° F. and thus it is ideally suited for use with nickel-chromium-based superalloy sheet metal components.
It is another object of the present invention to provide a brazed metal article in which the article has been brazed with a novel ternary nickel-gold-phosphorus brazing alloy.
It is another object of the present invention to provide a brazed superalloy metal sheet article in which the article has been brazed with a ternary nickel-gold-phosphorus brazing alloy.
It is another object of the present invention to provide a method for brazing metal components together using a novel ternary nickel-gold-phosphorus brazing alloy in which the brazing temperature is held 40° F. below the eutectic temperature of the ternary nickel-gold-phosphorus brazing alloy.
It is another object of the present invention to provide a method for brazing superalloy metal sheets together with a novel ternary nickel-gold-phosphorus brazing alloy at a brazing temperature below 1830° F. and preferably 100° F. below of the eutectic temperature of the ternary nickel-gold-phosphorus brazing alloy.
It is another object of the present invention to provide a novel ternary nickel-gold-phosphorus brazing alloy that is economical to use and having good strength, ductility, and corrosion/oxidation resistance characteristics.